Functionalized Cellulose with EDTA-like Chelating Groups for Removal of Heavy Metals

Functionalized Cellulose with EDTA-like Chelating Groups for Removal of Heavy Metals | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Functionalized Cellulose with EDTA-like Chelating Groups for Removal of Heavy Metals Lu Yang, Nan You, Baohong Ding This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3056356/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Cellulose is a renewable and promising material. However, native cellulose has to face the challenge of the removal of heavy metals with low efficiency which limits its application. In this work, a cellulose derivative with EDTA-like chelating groups is designed and prepared by the chemical grafting of cellulose. Cellulose is partially oxidized to dialdehyde cellulose which is treated with 20% excess of diethylenetriamine through a Schiff base reaction for the preparation of the aminated cellulose. The amine groups of the aminated cellulose are carboxymethylated by reacting with 20% excess of bromoacetic acid through a substitution reaction. A EDTA-like cellulose derivative functionalized with multidentate N,O‑donor atoms (EDTA-CL) is obtained for accessing the adsorptive property of Cd 2+ and Pb 2+ . The high-efficient adsorption of the both ions by the EDTA-CL with high adsorptive amounts (Pb 2+ : 438.3 mg g − 1 and Cd 2+ : 287.2 mg g − 1 ) can be accomplished by controlled parameters (pH in the range of 4–6 with contact time 30 min) using the dosage of 1 g L − 1 of the EDTA-CL in aqueous solution. The adsorptive processes of the both ions onto the EDTA-CL can be well fitted by pseudo-second-order and Langmuir equations. Thermodynamics data reveal that the adsorption of the both ions onto the EDTA-CL is a spontaneous and endothermic process. The loaded EDTA-CL by simple acid-base treatment can be regenerated 5 times with loss of adsorptive amounts (Cd 2+ : 14% and Pb 2+ : 17%). EDTA-like Chelation Cellulose Heavy metals Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Pb 2+ and Cd 2+ ions, typical heavy metals pollutants, are detected frequently in industrial and municipal wastewaters (Jiang et al, 2021 ). Non-biodegradable Pb 2+ and Cd 2+ ions as probable carcinogens can be accumulated in organisms, causing a serious threat for human health through food chain (Ye et al, 2021 ). The effective removal of the Pb 2+ and Cd 2+ ions from wastewaters has attracted considerable attention (Fu & Wang, 2011 ). The metal-bearing effluents with the high concentrations can be effectively treated by many methods (Fu & Wang, 2011 ), whereas adsorption becomes a highly efficient treatment for the metal-bearing effluents containing the low concentrations at the level of mg L − 1 (Gerente et al, 2007 ). In recent years, the adsorbents derived from the industrial/agricultural byproducts and the natural products with the advantages of high efficiency, low cost, abundant reserves, environmental friendliness, and biodegradability have attracted considerable attention for the removal of Pb 2+ and Cd 2+ ions (Thakur et al, 2020 ; Hegazi, 2013 ). Cellulose derivatives are increasingly utilized as the sorbents in pollutants control. The native cellulose with poor efficiency of the metal removal is due to the shortage of active binding sites. Usually, the cellulose modified with some functional groups (such as carboxyl (Kundu et al, 2019 ), amino (Navarro et al, 1999 ), sulphonic acid (Gülü et al, 2003 ), and sulfhydryl (Movaghgharnezhad et al, 2020 ) groups) through surface chemical modification exhibits better efficient for the metal removal than the native cellulose. Based on the rule of coordination chemistry, polydentate chelating ligands always exert the stronger affinity towards heavy metal ions than most monodentate ligands (Tisato et al, 1997 ). Thus, it is a good strategy to introduce some polydentate chelating ligands on the cellulose for enhancing the removal efficiency of heavy metals. Gurgel et al. ( 2008 ) reported a succinylated mercerized cellulose modified with triethylenetetramine with adsorption capacities of 87.0 mg g − 1 for Cd 2+ and 192.3 mg g − 1 for Pb 2+ . Ge et al. ( 2016 ) reported a composite of cellulose/poly(ethylene imine) with adsorptive amount of 248.2 mg g − 1 for Pb 2+ due to poly(ethylene imine) with abundant N-donating atoms as coordinate sites for effectively capturing heavy metal ions. Nongbe et al. ( 2018 ) reported that the cellulose grafted with spermine owned higher adsorption capacities for heavy metals than the cellulose grafted with ethylenediamine due to spermine with more N-donating atoms. Zhang et al. ( 2017 ) prepared a sorbent through grafting polyethylenimine (PEI) onto carboxylated microcrystalline cellulose with the high adsorption capacities of 217.3 mg g − 1 for Cd 2+ and 357.1 mg g − 1 for Pb 2+ due to the sorbent with abundant amino and carboxyl groups. Hu et al. ( 2021 ) prepared a cellulose grafted with EDTA-like groups which can coordinate with heavy metals and alkaline-earth metal and indicate good adsorption capacities (such as 80.3 mg g − 1 for Cu 2+ and 266.7 mg g − 1 for Pb 2+ ). The functional groups of the reactive cellulose derivatives usually were grafted through the direct substitution reaction on the cellulose units (Hokkanen et al, 2016 ). The functional groups can also be introduced by the Schiff base reaction between dialdehyde cellulose and the compounds containing the primary amine groups (Guo Kobayashi et al, 1990 ). Most importantly, the Schiff base polydentate chelating ligand exhibits a better complexing ability with metal ions (Fan et al, 2013 ; Fan et al, 2014 ), and is expected to exhibit unique superiority in removal of heavy metals. In this work, we proposed a strategy of promoting the adsorptive capacity of heavy metals using the chemical grafting of cellulose by amino acetic acid functions through Schiff base reaction between dialdehyde cellulose and diethylenetriamine, and substitution reaction which occurred mainly on the amine groups of polyamines with bromoacetic acid. We obtained three reactive cellulose derivatives modified with EDTA-like groups as the sorbents for the removal of heavy metals. The adsorptive performances of Cd 2+ and Pb 2+ by the three reactive cellulose derivatives have been compared in order to test the influence of the grafting density of the N- and O- donating atoms in the reactive cellulose derivatives. Both kinetic and equilibrium features of the adsorption of the Cd 2+ and Pb 2+ ions by the three reactive cellulose derivatives have been investigated. 2. Experimental 2.1 Chemicals All the chemicals are of analytical grade and were obtained from Sinopharm Chemical Reagent Co., Shanghai, China (Table S1 ). Solutions of Cd 2+ or Pb 2+ with the desired concentrations are prepared by dissolving the appropriate amount in deionized water. Dialysis bag (12, 000 MWCO, < 5 nm pore size) was purchased from Shanghai Yuanjv biological Technology Co., Ltd., Shanghai, China. 2.2 Preparation The dialdehyde cellulose is prepared through an oxidation reaction of microcrystalline cellulose as reported previously and its process is described in Supporting Information. The aldehyde content of the dialdehyde cellulose is determined by hydroxylamine hydrochloride method (Kim et al, 2004 ). 12 g of the dialdehyde cellulose with the content of the aldehyde groups of 2.8 mmol g –1 is obtained for the next step. The diethylenetriamine are grafted onto the dialdehyde cellulose surface though a Schiff base reaction. The dialdehyde cellulose (10 g) was dispersed in 200 mL diethylenetriamine solution with the molar ratio of aldehyde group to primary amino group at 1:1.2 at pH 3 using hydrothermal assisted method at 80°C for 2 h. The suspension was transferred into dialysis bag for the removal of excess diethylenetriamine with changing the deionized water once every 12 h for 5 days, and then freeze-dried to get 9 g of the aminated cellulose. The N content of the aminated cellulose (8.2 mmol g –1 ) is determinated by Kjeldahl method. 6 g of the aminated cellulose is dispersed in 100 mL N,N-dimethylformamide containing bromoacetic acid (13.9 g, 100 mmol) and sodium bicarbonate (8.4 g, 100 mmol) and was refluxed for 48 h by heating at 80°C to form the target product. And then the mixture is filtered, and then washed with deionized water for several times and freeze-dried to obtain the EDTA-like cellulose derivatives functionalized with imine and carboxyl groups (marked as EDTA-CL). The content of carboxylic groups in EDTA-CL is determined by conductometric titration (Zemljič et al, 2008 ). 2.3 Batch experiments The batch adsorption experiments are performed with a constant dosage of 1 g L − 1 for the sorbents in duplicate. The effects of different pH (3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0), and the various contact time (5, 10, 15, 20, 25, 30, 40, 50 and 60 min) on the adsorption of Cd 2+ or Pb 2+ ion by the EDTA-CL are tested with the initial Cd 2+ or Pb 2+ concentration of 800 mg L − 1 . Effects of initial concentrations of the both metal ions from 100 and 1000 mg L − 1 with an interval of 100 mg L − 1 are investigated at pH 5 for 30 min at the changeable temperature (15, 30 and 45°C). After adsorption, the mixture is filtered, and then the residual concentrations of the both metal ions in the filtrate are determined by flame atomic absorption spectrometry (A6300c, Shimadzu Corporation, Japan). The adsorptive amounts of the both metal ions are calculated as the Eq.S1 described in Supporting Information. The average values of metal concentrations are reported with the measurement at least three times. 2.4 Reuse The same sorbent is used in consecutive adsorption–desorption for testing the reusability of the EDTA-CL. The 0.2 mol L − 1 HCl solution is used as the eluent to desorb the metal ions on the loaded sorbents for 60 min as reported previously (Zhou et al, 2014 ). The regenerative efficiency (RE%) of the regenerative EDTA-CL for the adsorptive amounts of the both metal ions are also calculated as the Eq.S2. 3. Result and Discussion 3.1 Preparation of the EDTA-CL As seen Table S2, the content of N elements in the EDTA-CL by Kjeldahl method is found to be 8.1 mmol g –1 , which is near to the N density of the aminated cellulose, indicating no loss of N elements during the substitution process. The density of carboxyl group in the EDTA-CL is found to be 11.5 mmol g –1 . The preparation process of the EDTA-CL is illustrated in Scheme 1 . The aminated cellulose is obtained through a Schiff base reaction between diethylenetriamine and the dialdehyde cellulose. The target compound is synthesized through a substitution reaction between the aminated cellulose and bromoacetic acid. Carboxyl substitution reaction is carried out mainly on the groups primary and secondary amines of the aminated cellulose. These functional groups can play a leading role in the adsorptive removal of metal ions and coordinate with Cd 2+ or Pb 2+ ions to form several five membered rings which is a stable structure for metal complexes (Bicak et al, 2000 ). 3.2 Characterization The dialdehyde cellulose, aminated cellulose and EDTA-CL remain the characteristic of the fibrous structure in Fig. 1 . After the oxidation of microcrystalline cellulose (Fig. 1 a), the dialdehyde cellulose (Fig. 1 b) looks peeling. The surface morphology of the aminated cellulose becomes rough with wrinkles due to the grafted diethylenetriamine on the dialdehyde cellulose (Fig. 1 c). The EDTA-CL exhibits the rougher surface than the aminated cellulose (Fig. 1 d), which is attributed to the substitution of amino groups by bromoacetic acid. The change trend in the BET surface area proved the results from the SEM (Table S2). The BET surface area of the dialdehyde cellulose (7.8 m 2 g − 1 ) decreases slightly compared with microcrystalline cellulose (10.1 m 2 g − 1 ) due to the oxidation of sodium metaperiodate as reported previously (Yu et al, 2021 ). The BET surface areas of the aminated cellulose (21.6 m 2 g − 1 ) and EDTA-CL (28.8 m 2 g − 1 ) increase gradually due to the introduction of more side chains. There is no change in the crystalline nature for the microcrystalline cellulose, dialdehyde cellulose, aminated cellulose and EDTA-CL (Fig. 2 a). The diffraction peaks at 15.6°, 22.6° and 34.8° are attributed to the (1–10)/(101), (200) and (004) crystal faces of cellulose, respectively (French, 2014 ). The intensities for these peaks decrease due to the modification of cellulose. The similar phenomenon had been reported previously (Kumar & Sharma, 2019 ). From Fig. 2 b, for all the cellulose derivatives, the absorption peaks of at 3416 cm − 1 (the O–H stretching vibration), 2905 cm − 1 (the C–H stretching vibration), 1634 cm − 1 (the O–H bending vibration), 1374 cm − 1 (the C–H bending vibration), 1160 cm − 1 (the C–O stretching vibration), 1060 cm − 1 (the C–O–C stretching vibration) and 894 cm − 1 from β-glycosidic linkages between the sugar units are associated with the characteristic of backbone (Wang & Lu, 2020 ). From FT-IR spectra of the dialdehyde cellulose, the peak at 1733 cm − 1 is due to the C = O stretching vibration of aldehyde group in the dialdehyde cellulose. From FT-IR spectra of the aminated cellulose, the peak at 1733 cm − 1 disappears due to the grafting of diethylenetriamine on to the dialdehyde cellulose through a Schiff base reaction (Shen et al, 2015 ). These illustrate that the diethylenetriamine has been grafted successfully onto the dialdehyde cellulose through the Schiff base reaction. From FT-IR spectra of the EDTA-CL, the characteristic peak of the C = O stretching vibration from carboxyl groups is re-emerged at 1727 cm − 1 due to the substitution of bromoacetic acid on the amino groups (Liu et al, 2019 ). A slight change in the wavenumbers of the C = O stretching vibration from 1733 to 1727 cm − 1 is due to the change of functional groups from aldehyde group to carboxyl groups. These indicated that the EDTA-CL has been obtained. Solid state 13C NMR spectra of the EDTA-CL are indicated in Fig. 2 c. The three derivatives exhibit the characteristic peaks of cellulose at 105.5 ppm (C1), 88.1 ppm (C4), 75.1 ppm (C2, C3 and C5), and 62.8 ppm (C6), which are associated with six carbon atoms of the glucose unit of cellulose (Kono et al, 2002a ). A peak at 175 ppm is found due to the presence of carbonyl carbons of carboxyl groups in the EDTA-CL (Kono et al, 2002b ), which is consistent with the previous report (Varma et al, 1997 ), While the peaks at 61.6 and 42 ppm are due to the presence of two kinds of methylene carbon in diethylenetriamine and bromoacetic acid. The results of 13C NMR spectra agree well with the results from IR spectra. 3.3 pH Effect Figure 3 a depicts the effect of solution pH on the adsorptive amounts of metal ions by the cellulose modified with EDTA-like groups (EDTA-CL). The adsorptive amounts of the both metal ions strongly depend on the solution pH. When solution increased from 3 to 4, a remarkable increase in the adsorptive amounts of the Cd 2+ and Pb 2+ ions is observed. At low pH, the N-donor atoms of EDTA-CL are protonated and the carboxylic groups of EDTA-CL are almost in an undissociated state, resulting in that the chelating groups lose their coordination ability with metal ions. With increasing pH, the protonation of chelating groups is weak. Oppositely, the adsorptive amounts adsorbed of the both metal ions increase at higher pH. In the pH range of 4–6, the adsorptive amounts of the both metal ions keep constant, which is consistent with the same trend as reported previously (Berber, 2020 ; Wang et al, 2011 ). The high stable adsorptive amounts of the both metal ions in this pH range rule out the importance of coordination of N, O-donor atoms of the EDTA-CL with metal ions, which plays a positive role in the enhanced adsorption, while it will be effectively weakened in solution by the competition effect of H + ions with metal ions for the N, O-donor atoms of the EDTA-CL (Leyva-Ramos et al, 1997 ). The precipitation of Cd(OH) 2 or Pb(OH) 2 formation will happen easily at pH > 6 (Wei et al, 2015 ; Qu et al, 2021 ). Thus, the operational condition of pH is controlled at pH 5. 3.4 Effect of contact time Effect of contact time is characterized by an increase in the adsorptive amounts of the both metal ions with respect to time (Fig. 3 b). A remarkable increase in the adsorptive amounts of the both metal ions is found within 25 min due to lots of available chelating groups with the strong coordination, and then the steady state of their adsorptive amounts is observed after 25 min due to the exhaustion of the available chelating groups, illustrating that the EDTA-CL is saturated at this level. An optimum contact time of 30 min is sufficient for the adsorption of the both metal ions by the EDTA-CL for all the experiments. 3.5 Effect of initial concentrations Figure 3 c exhibits that the adsorptive amounts of the both metal ions are significant dependent of their initial concentrations in feed solution. The increase in the initial concentrations of Cd 2+ ions in the range of 100 − 500 mg L − 1 results in its enhanced adsorptive amounts from 95.7 to 257.9 mg g − 1 , indicating that there are lots of the active chelating sites in the EDTA-CL. And then the adsorptive amounts of Cd 2+ ions have no significant change with the increase of initial concentrations of Cd 2+ ions from 500 to 1000 mg L − 1 , which is probably related to a saturation of the chelating sites. Meanwhile, the EDTA-CL towards the adsorption of Pb 2+ ions exhibited a similar trend in the variation of adsorptive amounts on its initial concentrations (Fig. 4 c). The maximum adsorptive amounts of Pb 2+ and Cd 2+ ions by the EDTA-CL at 30°C are 438.3 and 287.2 mg g − 1 , respectively, which are higher than or comparable to those cellulose-based sorbents reported previously as indicated in Table 1 . There is a remarkable improvement in the adsorptive amounts through the chemical modification of cellulose due to the chelating groups on the rise. The same phenomena are reported previously (Nongbe et al, 2018 ; Zhang et al, 2017 ).. Table 1 Comparison of the adsorptive amounts of the reported cellulose-based sorbents for the Cd 2+ and Pb 2+ Cellulose-based sorbents Amounts (mg g − 1 ) References Cd 2+ Pb 2+ S-ligand tethered cellulose nanofibers 240.4 96.7 Abu-Danso et al, 2018 Cellulose -MnO 2 nanocomposite 67.4 290.8 Fu & Xie, 2019 Cellulose/poly(ethylene imine) composites - 248.2 Ge et al, 2016 Cellulose modified with succinic anhydride 86.0 205.9 Gurgel et al, 2008 Succinylated mercerized cellulose 87.0 192.3 Gurgel & Gil, 2009 Modified mercerized cellulose 149.0 333.0 Júnior et al, 2009 Guanyl-modified cellulose 68.0 52.0 Kenawy et al, 2018 Welan gum-modified cellulose 83.6 77.0 Liu et al, 2014 Cellulose paper grafted with polyamines - 131.6 Nongbe et al, 2018 Xanthated nano banana cellulose 154.3 - Pillai et al, 2013 Microwave-functionalized cellulose 151.5 295.2 Qu et al, 2020 Tannin-immobilized cellulose fiber 59.5 38.0 Taksitta et al, 2020 Cellulose nanofiber modified with iron 12.5 81.4 Vázquez-Guerrero et al, 2017 Carboxymethyl cellulose fiber 150.6 - Wei et al, 2015 Cellulose acetate/polyvinylpyrrolidone 34.7 31.0 Xiang et al, 2013 Amine functionalized cellulose 217.3 357.1 Zhang et al, 2017 EDTA-CL 287.2 438.3 This work 3.6 Effect of temperature There is a mild increase in the adsorptive amounts of Pb 2+ and Cd 2+ ions with the increase in temperature from 15 to 45°C (Fig. 4 ), which is attributed to the endothermic nature of the adsorption of the EDTA-CL for the both ions, illustrating that a higher temperature is favorable for the adsorption of the both ions by the EDTA-CL. 3.7 Isotherm The Freundlich (Freundlich, 1906 ), Langmuir (Langmuir, 1918 ) and Dubinin-Radushkevich (D-R) (Dubinin & Radushkevich, 1947 ) isotherms are used to fit the adsorptive data. From Table 2 , the adsorptive data of the both metal ions by the EDTA-CL are fitted satisfactorily with Langmuir model with high r 2 values (> 0.99), whereas the r 2 values of fitting curves using Freundlich and D-R models are relatively low. The highest K F values are obtained for Pb 2+ followed by Cd 2+ , while all the values of 1/ n fall in the range of 0–1 and are closer to 1, implying an effective adsorption with high strength (Tan et al, 2008 ; Kim et al, 2019 ). The E values of metal ions from D-R model (16.7 kJ mol − 1 for Pb 2+ , 13.1 kJ mol − 1 for Cd 2+ ) are higher than 8 kJ mol − 1 , illustrating that chemical adsorption of the EDTA-CL for the metal ions. The adsorptive amounts calculated from Langmuir model for Cd 2+ and Pb 2+ ions are 302.7 and 444.1 mg g − 1 , respectively, which have no significant difference with their experimental values. Therefore, the Langmuir model better fits the adsorption of the both metal ions by the EDTA-CL based on the above results. Similar adsorption behaviors for metal ions are found by the cellulose-based reported previously (Xu et al, 2021 ; Liu et al, 2021 ). Table 2 Isotherms parameters for the adsorption of ions by the EDTA-CL at 30°C Ions Freundlich Langmuir D–R Cd 2+ Pb 2+ K F = 59.7 L mg − 1 q max = 302.7 mg g − 1 E = 13.1 mol kJ − 1 n = 3.7 b = 0.037 L mg − 1 q s = 513.3 mg g − 1 R 2 = 0.9234 R 2 = 0.9993 R 2 = 0.9545 K F = 75.2 L mg − 1 q max = 444.1 mg g − 1 q s = 1117.2 mg g − 1 n = 2.9 b = 0.153 L mg − 1 E = 16.7 mol kJ − 1 R 2 = 0.9769 R 2 = 0.9990 R 2 = 0.9737 3.8 Kinetic The kinetic data of adsorption of the metal ions are fitted using pseudo-first-order model (PFOM) (Lagergren, 1898 ), pseudo-second-order model (PSOM) (Ho & McKay, 1999 ) and Elovich model (EM) (Low, 1960 ). The linear equations of these models are described in Supporting Information. In Table 3 , the PFOM and EM are not suitable for the description of the adsorption of the both ions by the EDTA-CL due to the low values of r 2 obtained from fitting curves of PFOM and EM. The values of r 2 derived from fitting curves of PSOM for the both ions are close to unity, whereas the calculated values and experimental values of the both ions by the EDTA-CL are very close to each other, illustrating that the PSOM can described well the adsorption of the EDTA-CL for the both ions. Table 3 Kinetic parameters for Cd 2+ and Pb 2+ at 30°C Ions PFOM PSOM EM k 1 = 0.070 min − 1 k 2 = 1.13×10 − 3 g mg − 1 min − 1 α = 955.8 mg·g − 1 ·min − 1 Cd 2+ q e = 99.3 mg g − 1 q e = 277.8 mg g − 1 β = 0.027 r 2 = 0.9509 r 2 = 0.9993 r 2 = 0.9325 k 1 = 0.099 min − 1 k 2 = 0.91×10 − 3 g mg − 1 min − 1 α = 2748.7 mg·g − 1 ·min − 1 Pb 2+ q e = 146.7 mg g − 1 q e = 434.8 mg g − 1 β = 0.019 r 2 = 0.9014 r 2 = 0.9990 r 2 = 0.8934 3.9 Thermodynamics The calculated equations of Gibbs free energy change (Δ G 0 ), enthalpy change (Δ H 0 ) and entropy change (Δ S 0 ) are calculated as reported previously (Liu, 2009 ) and described in Supporting Information. In Table 4 , the values of ln b from Langmuir constant increase as the temperature from 15 to 45°C, which leads to the increase of the Δ G 0 values in the negative direction. These confirm that the adsorption of the EDTA-CL for the both ions is more spontaneous at higher temperature. The values of Δ H 0 and Δ S 0 for the both ions are positive, illustrating that the adsorption is endothermic and the randomness at the solid/solution interface is increased during the adsorption. These result in more adsorption at higher temperature. Table 4 Thermodynamic parameters for adsorption of the Cd 2+ and Pb 2+ ions Constants Cd 2+ Pb 2+ 15 ° C 30 ° C 45 ° C 15 ° C 30 ° C 45 ° C ln b 7.95 8.32 8.64 9.62 10.36 10.65 Δ G o a -23.0 -26.1 -28.2 -19.1 -21.0 -22.9 Δ H o b 26.4 17.5 Δ S o c 172.0 126.9 a Unit: kJ mol − 1 ; b Unit: kJ mol − 1 ; c Unit: J mol − 1 K − 1 3.10 Reusability 0.2 mol L − 1 HCl is used as the eluents to desorb the both ions from the loaded EDTA-CL with stirring for 1 h at room temperature and is shown 98.8% of Pb 2+ and 97.9% of Cd 2+ desorption. Figure 5 exhibits the adsorptive amounts of Cd 2+ and Pb 2+ ions by the regenerated EDTA-CL over five successive adsorption–desorption cycles. The adsorptive amounts of the both ions drop per cycle of reuse. But even it remains 86.5% for Cd 2+ ions and 83.7% for Pb 2+ ions of the virgin at the end of 5th cycle. The EDS mapping of the N elements in the regenerated EDTA-CL is exhibited in Figure S1 , indicating that the N elements is uniformly dispersed on the surface of cellulose. The N contents of the regenerated EDTA-CL are found to be in the range of 7.1–7.5 mmol g –1 (Table S3). A decrease in the N contents of the regenerated EDTA-CL with the increase of the cycle numbers is observed. Compared with the N contents of the virgin (8.1mmol g –1 ), the loss of N elements is relatively low, which is consistent with the change in the values of RE%. These results illustrate that the EDTA-CL can be reused for several times without significant loss of the adsorptive amounts for the both ions. 4. Conclusion EDTA-CL, an EDTA-like chelating material derived from cellulose, is obtained by the chemical grafting of amino acetic acid groups onto the cellulose through the Schiff base and substitution reaction. The EDTA-CL shows rapid chelation with Cd 2+ and Pb 2+ , high adsorptive amounts, and good regeneration. The EDTA-CL had a relatively large adsorptive amounts of 302.7 mg g − 1 for Cd 2+ and 444.1 mg g − 1 for Pb 2+ , as compared to many cellulose derivatives reported in the literatures. The EDTA-CL can offer chelating groups as effective binding sites and a homogenous surface for the adsorption of the both ions, leading to Langmuir model better fitting to the adsorptive behavior. The kinetic and thermodynamics fitting results means that an endothermic and spontaneous chemisorption between the N,O‑donor atoms on the surface of the EDTA-CL and the both ions is a rate-limiting step. Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Availability of data and materials The Supporting Information is available free of charge on the Springer Publications website at DOI: Competing interests No conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. Funding This work is supported by Scientific Foundation of Liaoning Education Department (LJKZZ20220053). Authors' contributions Lu Yang: Investigation, Formal analysis, Data curation, Writing-Original draft preparation. Baohong Ding: Methodology, Formal analysis, Writing-Original draft preparation. Nan You: Conceptualization, Project administration Validation, Resources, Data curation. Acknowledgements Not applicable. References Abu-Danso, E., Peräniemi, S., Leiviskä, T., Bhatnagar, A. 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Thakur, V., Sharma, E., Guleria, A., Sangar, S., Singh, K. (2020) Modification and management of lignocellulosic waste as an ecofriendly biosorbent for the application of heavy metal ions sorption. Materials Today: Proceedings 32, 608–619. Tisato, F., Refosco, F., Ossola, F., Bolzati, C., Bandoli, G. (1997) Cheminform abstract: polydentate phosphinoamine ligands: a class of efficient chelating agents for the stabilization of various technetium(v) and rhenium(v) cores. Transition Metal Chemistry 22, 606–607. Varma, A.J., Chavan, V.B., Rajmohanan, P.R., Ganapathy, S. (1997) Some observations on the high-resolution solid-state CP-MAS carbon-13 NMR spectra of periodate-oxidized cellulose. Polymer Degradation & Stability 58, 257–260. Vázquez-Guerrero, A., Cortés-Martínez, R., Alfaro-Cuevas-Villanueva, R., Rivera-Muñoz, E.M., Huirache-Acuña, R. (2021) Cd(II) and Pb(II) Adsorption using a composite obtained from moringa oleifera Lam. cellulose nanofibrils impregnated with iron nanoparticles, Water, 13, 89. Wang, H., Yu, Y.-F., Chen, Q.-W., Cheng, K. (2011) Carboxyl-functionalized nanoparticles with magnetic core and mesopore carbon shell as adsorbents for the removal of heavy metal ions from aqueous solution. Dalton Trans 40, 559–563. Wang, Y., Lu, Q. (2020) Dendrimer functionalized nanocrystalline cellulose for Cu(II) removal, Cellulose 27, 2173–2187. Wei, W., Kim, S., Song, M.H., Bediako, J.K., Yun, Y.S. (2015) Carboxymethyl cellulose fiber as a fast binding and biodegradable adsorbent of heavy metals. Journal of the Taiwan Institute of Chemical Engineers 57, 104–110. Xiang, T., Zhang, Z.L., Liu, H.Q., Yin, Z.Z., Li, L., Liu, X.M. (2013) Characterization of cellulose-based electrospun nanofiber membrane and its adsorptive behaviours using Cu(II), Cd(II), Pb(II) as models. Science China Chemistry 56, 567–575. Xu, X., Ouyang, X., Yang, L. (2021) Adsorption of Pb(II) from aqueous solutions using crosslinked carboxylated chitosan/carboxylated nanocellulose hydrogel beads, Journal of Molecular Liquids 322, 114523. Ye, X., Zheng, X., Zhang, D., Niu, X., Zhou, S. (2021) The efficient biomineralization and adsorption of cadmium (Cd 2+ ) using secretory organo-biominerals (sobs) produced by screened alcaligenes faecalis k2. Environmental Research, 199, 111330. Yu, H., Zheng, L., Zhang, T., Ren, J., Cheng, W., Zhang, L., Meng, P. (2021) Adsorption behavior of Cd (II) on TEMPO-oxidized cellulose in inorganic/organic complex systems. Environmental Research 195, 110848. Zemljič, L.F., Peršin, Z., Stenius, P., Kleinschek, K.S. (2008) Carboxyl groups in pre-treated regenerated cellulose fibres. Cellulose 15, 681–690. Zhang, C., Su, J., Zhu, H., Xiong, J., Liu, X., Li, D., Chen, Y., Li, Y. (2017) The removal of heavy metal ions from aqueous solutions by amine functionalized cellulose pretreated with microwave-H 2 O 2 . RSC Advances 7, 34182–34191. Zhou, Y., Wang, X., Zhang, M., Jin, Q., Gao, B., Ma, T. (2014) Removal of Pb(II) and malachite green from aqueous solution by modified cellulose, Cellulose 21, 2797–2809. Scheme Scheme 1 is available in Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Scheme1.jpg The preparation process of the EDTA-CL. EDTASupportingInformation23.6.12.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3056356","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":210562344,"identity":"100ee4af-641b-4625-bffd-fb5dc4f13e35","order_by":0,"name":"Lu Yang","email":"","orcid":"","institution":"Liaoning Petrochemical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lu","middleName":"","lastName":"Yang","suffix":""},{"id":210562345,"identity":"cb970920-b29b-439f-827b-7c509eee3009","order_by":1,"name":"Nan You","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAv0lEQVRIiWNgGAWjYBCD+v3HGxsffiBFC2PDmcPNxhKkabmR3ibAQ4xSg+M9Zg9+7mBgZpz5sI1BgsFOTreBkJYzZ8wNe88wsDFLJ7Y9KGBINjY7QEjLjRwzCd42Bh426cR2AwmGA4nbiNEi+RfoJB7Jg20SPMRqkQbaYiAhwUikFskzx8qkZdsYEgx4EoGBbECEX/iON2+TfAvSwn784cMPFXZyBLUoQBT8h7mTgHIQkG8gQtEoGAWjYBSMcAAAoBA/SO5qBh8AAAAASUVORK5CYII=","orcid":"","institution":"Liaoning Petrochemical University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Nan","middleName":"","lastName":"You","suffix":""},{"id":210562346,"identity":"9bafb1ae-43ed-4d2e-9f94-984f0083cf3a","order_by":2,"name":"Baohong Ding","email":"","orcid":"","institution":"Liaoning Petrochemical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Baohong","middleName":"","lastName":"Ding","suffix":""}],"badges":[],"createdAt":"2023-06-13 06:44:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3056356/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3056356/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":39106408,"identity":"6a17ff05-d3d8-43b6-8446-ddeb3b9d9849","added_by":"auto","created_at":"2023-06-26 18:21:16","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1632709,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of the (a) microcrystalline cellulose, (b) dialdehyde cellulose, (c) aminated celluloseand (d) EDTA-CL.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/dd26267b040a4a4e108c63ab.jpg"},{"id":39105511,"identity":"f4583360-bb58-4b17-a566-2506e8256e72","added_by":"auto","created_at":"2023-06-26 18:13:16","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1565646,"visible":true,"origin":"","legend":"\u003cp\u003e(a) XRD curves of the microcrystalline cellulose, dialdehyde cellulose, aminated celluloseand EDTA-CL; (b) IR spectra of the dialdehyde cellulose, aminated celluloseand EDTA-CL; (c) 13C-NMR spectrum of the EDTA-CL.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/0537115633a15936a3a0a79b.jpg"},{"id":39107809,"identity":"21483ed9-6c96-4309-8062-421950873ece","added_by":"auto","created_at":"2023-06-26 18:29:16","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":130066,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Effects of solution pH on the amounts adsorbed for the both ions: Concentration of ions = 800 mg L\u003csup\u003e−1\u003c/sup\u003e, time = 30 min, volume of solution= 20.0 mL, dosage of sorbent= 1 g L\u003csup\u003e−1\u003c/sup\u003e, temperature = 30 °C; (b) Effects of contact time on the adsorptive amounts for the both ions: Concentration of metals = 800 mg L\u003csup\u003e−1\u003c/sup\u003e, pH= 5, volume of solution= 20.0 mL, dosage of sorbent= 1 g L\u003csup\u003e−1\u003c/sup\u003e, temperature = 30 °C; (c) Amounts adsorbed of Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e by the EDTA-CL: Time = 30 min, pH=5, volume of solution= 20.0 mL, dosage of sorbent= 1 g L\u003csup\u003e−1\u003c/sup\u003e, temperature = 30 °C.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/e1e7e30cb5b429fdd9d75b51.jpg"},{"id":39105516,"identity":"0dced97f-4830-48ef-ad5b-c62b3b80cdc4","added_by":"auto","created_at":"2023-06-26 18:13:16","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":211301,"visible":true,"origin":"","legend":"\u003cp\u003eInfluences of temperature on the amounts adsorbed of (e) Cd\u003csup\u003e2+\u003c/sup\u003e and (f) Pb\u003csup\u003e2+\u003c/sup\u003e by the EDTA-CL: Time = 30 min, pH=5, volume of solution= 20.0 mL, dosage of sorbent= 1 g L\u003csup\u003e−1\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/73ee01da66c6c55a00c9e9ab.jpg"},{"id":39105517,"identity":"edecdb48-713a-49b1-b645-c7b6c692b3fa","added_by":"auto","created_at":"2023-06-26 18:13:17","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":156171,"visible":true,"origin":"","legend":"\u003cp\u003eRegeneration of the EDTA-CL.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/c6bca9cb2ab0ece97303f8ef.jpg"},{"id":43973266,"identity":"8925d78a-f220-49e4-a922-14e9ffa2cdcf","added_by":"auto","created_at":"2023-10-02 14:37:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":866167,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/7ce3f8c9-186f-4bb1-92bb-783bcba63cea.pdf"},{"id":39105515,"identity":"94aec26f-58bb-45ba-bcc6-b792d64925a9","added_by":"auto","created_at":"2023-06-26 18:13:16","extension":"jpg","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":99040,"visible":true,"origin":"","legend":"\u003cp\u003eThe preparation process of the EDTA-CL.\u003c/p\u003e","description":"","filename":"Scheme1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/6cbe4528808aa48d9e834830.jpg"},{"id":39106409,"identity":"b868532b-881b-4fe0-8ea5-ecf04a124694","added_by":"auto","created_at":"2023-06-26 18:21:16","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":95683,"visible":true,"origin":"","legend":"","description":"","filename":"EDTASupportingInformation23.6.12.docx","url":"https://assets-eu.researchsquare.com/files/rs-3056356/v1/07a039e0fb6039d273aa6ef2.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Functionalized Cellulose with EDTA-like Chelating Groups for Removal of Heavy Metals","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003ePb\u003csup\u003e2+\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e ions, typical heavy metals pollutants, are detected frequently in industrial and municipal wastewaters (Jiang et al, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Non-biodegradable Pb\u003csup\u003e2+\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e ions as probable carcinogens can be accumulated in organisms, causing a serious threat for human health through food chain (Ye et al, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The effective removal of the Pb\u003csup\u003e2+\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e ions from wastewaters has attracted considerable attention (Fu \u0026amp; Wang, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The metal-bearing effluents with the high concentrations can be effectively treated by many methods (Fu \u0026amp; Wang, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), whereas adsorption becomes a highly efficient treatment for the metal-bearing effluents containing the low concentrations at the level of mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Gerente et al, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn recent years, the adsorbents derived from the industrial/agricultural byproducts and the natural products with the advantages of high efficiency, low cost, abundant reserves, environmental friendliness, and biodegradability have attracted considerable attention for the removal of Pb\u003csup\u003e2+\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e ions (Thakur et al, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Hegazi, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Cellulose derivatives are increasingly utilized as the sorbents in pollutants control. The native cellulose with poor efficiency of the metal removal is due to the shortage of active binding sites. Usually, the cellulose modified with some functional groups (such as carboxyl (Kundu et al, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), amino (Navarro et al, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1999\u003c/span\u003e), sulphonic acid (G\u0026uuml;l\u0026uuml; et al, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2003\u003c/span\u003e), and sulfhydryl (Movaghgharnezhad et al, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) groups) through surface chemical modification exhibits better efficient for the metal removal than the native cellulose. Based on the rule of coordination chemistry, polydentate chelating ligands always exert the stronger affinity towards heavy metal ions than most monodentate ligands (Tisato et al, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). Thus, it is a good strategy to introduce some polydentate chelating ligands on the cellulose for enhancing the removal efficiency of heavy metals. Gurgel et al. (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) reported a succinylated mercerized cellulose modified with triethylenetetramine with adsorption capacities of 87.0 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Cd\u003csup\u003e2+\u003c/sup\u003e and 192.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb\u003csup\u003e2+\u003c/sup\u003e. Ge et al. (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) reported a composite of cellulose/poly(ethylene imine) with adsorptive amount of 248.2 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb\u003csup\u003e2+\u003c/sup\u003e due to poly(ethylene imine) with abundant N-donating atoms as coordinate sites for effectively capturing heavy metal ions. Nongbe et al. (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) reported that the cellulose grafted with spermine owned higher adsorption capacities for heavy metals than the cellulose grafted with ethylenediamine due to spermine with more N-donating atoms. Zhang et al. (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) prepared a sorbent through grafting polyethylenimine (PEI) onto carboxylated microcrystalline cellulose with the high adsorption capacities of 217.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Cd\u003csup\u003e2+\u003c/sup\u003e and 357.1 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb\u003csup\u003e2+\u003c/sup\u003e due to the sorbent with abundant amino and carboxyl groups. Hu et al. (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) prepared a cellulose grafted with EDTA-like groups which can coordinate with heavy metals and alkaline-earth metal and indicate good adsorption capacities (such as 80.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Cu\u003csup\u003e2+\u003c/sup\u003e and 266.7 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb\u003csup\u003e2+\u003c/sup\u003e). The functional groups of the reactive cellulose derivatives usually were grafted through the direct substitution reaction on the cellulose units (Hokkanen et al, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The functional groups can also be introduced by the Schiff base reaction between dialdehyde cellulose and the compounds containing the primary amine groups (Guo Kobayashi et al, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). Most importantly, the Schiff base polydentate chelating ligand exhibits a better complexing ability with metal ions (Fan et al, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Fan et al, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), and is expected to exhibit unique superiority in removal of heavy metals.\u003c/p\u003e \u003cp\u003eIn this work, we proposed a strategy of promoting the adsorptive capacity of heavy metals using the chemical grafting of cellulose by amino acetic acid functions through Schiff base reaction between dialdehyde cellulose and diethylenetriamine, and substitution reaction which occurred mainly on the amine groups of polyamines with bromoacetic acid. We obtained three reactive cellulose derivatives modified with EDTA-like groups as the sorbents for the removal of heavy metals. The adsorptive performances of Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e by the three reactive cellulose derivatives have been compared in order to test the influence of the grafting density of the N- and O- donating atoms in the reactive cellulose derivatives. Both kinetic and equilibrium features of the adsorption of the Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e ions by the three reactive cellulose derivatives have been investigated.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Chemicals\u003c/h2\u003e \u003cp\u003eAll the chemicals are of analytical grade and were obtained from Sinopharm Chemical Reagent Co., Shanghai, China (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Solutions of Cd\u003csup\u003e2+\u003c/sup\u003e or Pb\u003csup\u003e2+\u003c/sup\u003e with the desired concentrations are prepared by dissolving the appropriate amount in deionized water. Dialysis bag (12, 000 MWCO, \u0026lt; 5 nm pore size) was purchased from Shanghai Yuanjv biological Technology Co., Ltd., Shanghai, China.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Preparation\u003c/h2\u003e \u003cp\u003eThe dialdehyde cellulose is prepared through an oxidation reaction of microcrystalline cellulose as reported previously and its process is described in Supporting Information. The aldehyde content of the dialdehyde cellulose is determined by hydroxylamine hydrochloride method (Kim et al, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). 12 g of the dialdehyde cellulose with the content of the aldehyde groups of 2.8 mmol g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e is obtained for the next step. The diethylenetriamine are grafted onto the dialdehyde cellulose surface though a Schiff base reaction. The dialdehyde cellulose (10 g) was dispersed in 200 mL diethylenetriamine solution with the molar ratio of aldehyde group to primary amino group at 1:1.2 at pH 3 using hydrothermal assisted method at 80\u0026deg;C for 2 h. The suspension was transferred into dialysis bag for the removal of excess diethylenetriamine with changing the deionized water once every 12 h for 5 days, and then freeze-dried to get 9 g of the aminated cellulose. The N content of the aminated cellulose (8.2 mmol g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e) is determinated by Kjeldahl method. 6 g of the aminated cellulose is dispersed in 100 mL N,N-dimethylformamide containing bromoacetic acid (13.9 g, 100 mmol) and sodium bicarbonate (8.4 g, 100 mmol) and was refluxed for 48 h by heating at 80\u0026deg;C to form the target product. And then the mixture is filtered, and then washed with deionized water for several times and freeze-dried to obtain the EDTA-like cellulose derivatives functionalized with imine and carboxyl groups (marked as EDTA-CL). The content of carboxylic groups in EDTA-CL is determined by conductometric titration (Zemljič et al, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Batch experiments\u003c/h2\u003e \u003cp\u003eThe batch adsorption experiments are performed with a constant dosage of 1 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the sorbents in duplicate. The effects of different pH (3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0), and the various contact time (5, 10, 15, 20, 25, 30, 40, 50 and 60 min) on the adsorption of Cd\u003csup\u003e2+\u003c/sup\u003e or Pb\u003csup\u003e2+\u003c/sup\u003e ion by the EDTA-CL are tested with the initial Cd\u003csup\u003e2+\u003c/sup\u003e or Pb\u003csup\u003e2+\u003c/sup\u003e concentration of 800 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Effects of initial concentrations of the both metal ions from 100 and 1000 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with an interval of 100 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are investigated at pH 5 for 30 min at the changeable temperature (15, 30 and 45\u0026deg;C). After adsorption, the mixture is filtered, and then the residual concentrations of the both metal ions in the filtrate are determined by flame atomic absorption spectrometry (A6300c, Shimadzu Corporation, Japan). The adsorptive amounts of the both metal ions are calculated as the Eq.S1 described in Supporting Information. The average values of metal concentrations are reported with the measurement at least three times.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Reuse\u003c/h2\u003e \u003cp\u003eThe same sorbent is used in consecutive adsorption\u0026ndash;desorption for testing the reusability of the EDTA-CL. The 0.2 mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl solution is used as the eluent to desorb the metal ions on the loaded sorbents for 60 min as reported previously (Zhou et al, \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The regenerative efficiency (RE%) of the regenerative EDTA-CL for the adsorptive amounts of the both metal ions are also calculated as the Eq.S2.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Result and Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Preparation of the EDTA-CL\u003c/h2\u003e \u003cp\u003eAs seen Table S2, the content of N elements in the EDTA-CL by Kjeldahl method is found to be 8.1 mmol g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e, which is near to the N density of the aminated cellulose, indicating no loss of N elements during the substitution process. The density of carboxyl group in the EDTA-CL is found to be 11.5 mmol g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e. The preparation process of the EDTA-CL is illustrated in Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The aminated cellulose is obtained through a Schiff base reaction between diethylenetriamine and the dialdehyde cellulose. The target compound is synthesized through a substitution reaction between the aminated cellulose and bromoacetic acid. Carboxyl substitution reaction is carried out mainly on the groups primary and secondary amines of the aminated cellulose. These functional groups can play a leading role in the adsorptive removal of metal ions and coordinate with Cd\u003csup\u003e2+\u003c/sup\u003e or Pb\u003csup\u003e2+\u003c/sup\u003e ions to form several five membered rings which is a stable structure for metal complexes (Bicak et al, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2000\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Characterization\u003c/h2\u003e \u003cp\u003eThe dialdehyde cellulose, aminated cellulose and EDTA-CL remain the characteristic of the fibrous structure in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. After the oxidation of microcrystalline cellulose (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea), the dialdehyde cellulose (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb) looks peeling. The surface morphology of the aminated cellulose becomes rough with wrinkles due to the grafted diethylenetriamine on the dialdehyde cellulose (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). The EDTA-CL exhibits the rougher surface than the aminated cellulose (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed), which is attributed to the substitution of amino groups by bromoacetic acid. The change trend in the BET surface area proved the results from the SEM (Table S2). The BET surface area of the dialdehyde cellulose (7.8 m\u003csup\u003e2\u003c/sup\u003eg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) decreases slightly compared with microcrystalline cellulose (10.1 m\u003csup\u003e2\u003c/sup\u003eg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) due to the oxidation of sodium metaperiodate as reported previously (Yu et al, \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The BET surface areas of the aminated cellulose (21.6 m\u003csup\u003e2\u003c/sup\u003eg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and EDTA-CL (28.8 m\u003csup\u003e2\u003c/sup\u003eg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) increase gradually due to the introduction of more side chains.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThere is no change in the crystalline nature for the microcrystalline cellulose, dialdehyde cellulose, aminated cellulose and EDTA-CL (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). The diffraction peaks at 15.6\u0026deg;, 22.6\u0026deg; and 34.8\u0026deg; are attributed to the (1\u0026ndash;10)/(101), (200) and (004) crystal faces of cellulose, respectively (French, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The intensities for these peaks decrease due to the modification of cellulose. The similar phenomenon had been reported previously (Kumar \u0026amp; Sharma, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFrom Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, for all the cellulose derivatives, the absorption peaks of at 3416 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (the O\u0026ndash;H stretching vibration), 2905 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (the C\u0026ndash;H stretching vibration), 1634 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (the O\u0026ndash;H bending vibration), 1374 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (the C\u0026ndash;H bending vibration), 1160 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (the C\u0026ndash;O stretching vibration), 1060 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (the C\u0026ndash;O\u0026ndash;C stretching vibration) and 894 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e from β-glycosidic linkages between the sugar units are associated with the characteristic of backbone (Wang \u0026amp; Lu, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). From FT-IR spectra of the dialdehyde cellulose, the peak at 1733 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to the C\u0026thinsp;=\u0026thinsp;O stretching vibration of aldehyde group in the dialdehyde cellulose. From FT-IR spectra of the aminated cellulose, the peak at 1733 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e disappears due to the grafting of diethylenetriamine on to the dialdehyde cellulose through a Schiff base reaction (Shen et al, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). These illustrate that the diethylenetriamine has been grafted successfully onto the dialdehyde cellulose through the Schiff base reaction. From FT-IR spectra of the EDTA-CL, the characteristic peak of the C\u0026thinsp;=\u0026thinsp;O stretching vibration from carboxyl groups is re-emerged at 1727 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e due to the substitution of bromoacetic acid on the amino groups (Liu et al, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). A slight change in the wavenumbers of the C\u0026thinsp;=\u0026thinsp;O stretching vibration from 1733 to 1727 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to the change of functional groups from aldehyde group to carboxyl groups. These indicated that the EDTA-CL has been obtained.\u003c/p\u003e \u003cp\u003eSolid state 13C NMR spectra of the EDTA-CL are indicated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec. The three derivatives exhibit the characteristic peaks of cellulose at 105.5 ppm (C1), 88.1 ppm (C4), 75.1 ppm (C2, C3 and C5), and 62.8 ppm (C6), which are associated with six carbon atoms of the glucose unit of cellulose (Kono et al, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2002a\u003c/span\u003e). A peak at 175 ppm is found due to the presence of carbonyl carbons of carboxyl groups in the EDTA-CL (Kono et al, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2002b\u003c/span\u003e), which is consistent with the previous report (Varma et al, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1997\u003c/span\u003e), While the peaks at 61.6 and 42 ppm are due to the presence of two kinds of methylene carbon in diethylenetriamine and bromoacetic acid. The results of 13C NMR spectra agree well with the results from IR spectra.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.3 pH Effect\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea depicts the effect of solution pH on the adsorptive amounts of metal ions by the cellulose modified with EDTA-like groups (EDTA-CL). The adsorptive amounts of the both metal ions strongly depend on the solution pH. When solution increased from 3 to 4, a remarkable increase in the adsorptive amounts of the Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e ions is observed. At low pH, the N-donor atoms of EDTA-CL are protonated and the carboxylic groups of EDTA-CL are almost in an undissociated state, resulting in that the chelating groups lose their coordination ability with metal ions. With increasing pH, the protonation of chelating groups is weak. Oppositely, the adsorptive amounts adsorbed of the both metal ions increase at higher pH. In the pH range of 4\u0026ndash;6, the adsorptive amounts of the both metal ions keep constant, which is consistent with the same trend as reported previously (Berber, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Wang et al, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The high stable adsorptive amounts of the both metal ions in this pH range rule out the importance of coordination of N, O-donor atoms of the EDTA-CL with metal ions, which plays a positive role in the enhanced adsorption, while it will be effectively weakened in solution by the competition effect of H\u003csup\u003e+\u003c/sup\u003e ions with metal ions for the N, O-donor atoms of the EDTA-CL (Leyva-Ramos et al, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). The precipitation of Cd(OH)\u003csub\u003e2\u003c/sub\u003e or Pb(OH)\u003csub\u003e2\u003c/sub\u003e formation will happen easily at pH\u0026thinsp;\u0026gt;\u0026thinsp;6 (Wei et al, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Qu et al, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Thus, the operational condition of pH is controlled at pH 5.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Effect of contact time\u003c/h2\u003e \u003cp\u003eEffect of contact time is characterized by an increase in the adsorptive amounts of the both metal ions with respect to time (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). A remarkable increase in the adsorptive amounts of the both metal ions is found within 25 min due to lots of available chelating groups with the strong coordination, and then the steady state of their adsorptive amounts is observed after 25 min due to the exhaustion of the available chelating groups, illustrating that the EDTA-CL is saturated at this level. An optimum contact time of 30 min is sufficient for the adsorption of the both metal ions by the EDTA-CL for all the experiments.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Effect of initial concentrations\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec exhibits that the adsorptive amounts of the both metal ions are significant dependent of their initial concentrations in feed solution. The increase in the initial concentrations of Cd\u003csup\u003e2+\u003c/sup\u003e ions in the range of 100\u0026thinsp;\u0026minus;\u0026thinsp;500 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e results in its enhanced adsorptive amounts from 95.7 to 257.9 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, indicating that there are lots of the active chelating sites in the EDTA-CL. And then the adsorptive amounts of Cd\u003csup\u003e2+\u003c/sup\u003e ions have no significant change with the increase of initial concentrations of Cd\u003csup\u003e2+\u003c/sup\u003e ions from 500 to 1000 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which is probably related to a saturation of the chelating sites. Meanwhile, the EDTA-CL towards the adsorption of Pb\u003csup\u003e2+\u003c/sup\u003e ions exhibited a similar trend in the variation of adsorptive amounts on its initial concentrations (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). The maximum adsorptive amounts of Pb\u003csup\u003e2+\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e ions by the EDTA-CL at 30\u0026deg;C are 438.3 and 287.2 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively, which are higher than or comparable to those cellulose-based sorbents reported previously as indicated in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There is a remarkable improvement in the adsorptive amounts through the chemical modification of cellulose due to the chelating groups on the rise. The same phenomena are reported previously (Nongbe et al, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Zhang et al, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2017\u003c/span\u003e)..\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the adsorptive amounts of the reported cellulose-based sorbents for the Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCellulose-based sorbents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eAmounts (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eReferences\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCd\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePb\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS-ligand tethered cellulose nanofibers\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e240.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAbu-Danso et al, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2018\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose -MnO\u003csub\u003e2\u003c/sub\u003e nanocomposite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e290.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFu \u0026amp; Xie, 2019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose/poly(ethylene imine) composites\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e248.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGe et al, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose modified with succinic anhydride\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e86.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e205.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGurgel et al, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSuccinylated mercerized cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e192.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGurgel \u0026amp; Gil, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2009\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModified mercerized cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e149.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e333.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eJ\u0026uacute;nior et al, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGuanyl-modified cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eKenawy et al, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWelan gum-modified cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e77.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLiu et al, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2014\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose paper grafted with polyamines\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e131.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNongbe et al, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2018\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eXanthated nano banana cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e154.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePillai et al, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2013\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMicrowave-functionalized cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e151.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e295.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eQu et al, 2020\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTannin-immobilized cellulose fiber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTaksitta et al, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose nanofiber modified with iron\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eV\u0026aacute;zquez-Guerrero et al, 2017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarboxymethyl cellulose fiber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e150.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWei et al, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2015\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose acetate/polyvinylpyrrolidone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eXiang et al, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2013\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAmine functionalized cellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e217.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e357.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eZhang et al, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2017\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEDTA-CL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e287.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e438.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThis work\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Effect of temperature\u003c/h2\u003e \u003cp\u003eThere is a mild increase in the adsorptive amounts of Pb\u003csup\u003e2+\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e ions with the increase in temperature from 15 to 45\u0026deg;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), which is attributed to the endothermic nature of the adsorption of the EDTA-CL for the both ions, illustrating that a higher temperature is favorable for the adsorption of the both ions by the EDTA-CL.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.7 Isotherm\u003c/h2\u003e \u003cp\u003eThe Freundlich (Freundlich, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1906\u003c/span\u003e), Langmuir (Langmuir, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1918\u003c/span\u003e) and Dubinin-Radushkevich (D-R) (Dubinin \u0026amp; Radushkevich, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1947\u003c/span\u003e) isotherms are used to fit the adsorptive data. From Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the adsorptive data of the both metal ions by the EDTA-CL are fitted satisfactorily with Langmuir model with high \u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e values (\u0026gt;\u0026thinsp;0.99), whereas the \u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e values of fitting curves using Freundlich and D-R models are relatively low. The highest K\u003csub\u003eF\u003c/sub\u003e values are obtained for Pb\u003csup\u003e2+\u003c/sup\u003e followed by Cd\u003csup\u003e2+\u003c/sup\u003e, while all the values of 1/\u003cem\u003en\u003c/em\u003e fall in the range of 0\u0026ndash;1 and are closer to 1, implying an effective adsorption with high strength (Tan et al, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Kim et al, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The \u003cem\u003eE\u003c/em\u003e values of metal ions from D-R model (16.7 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb\u003csup\u003e2+\u003c/sup\u003e, 13.1 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Cd\u003csup\u003e2+\u003c/sup\u003e) are higher than 8 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, illustrating that chemical adsorption of the EDTA-CL for the metal ions. The adsorptive amounts calculated from Langmuir model for Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e ions are 302.7 and 444.1 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively, which have no significant difference with their experimental values. Therefore, the Langmuir model better fits the adsorption of the both metal ions by the EDTA-CL based on the above results. Similar adsorption behaviors for metal ions are found by the cellulose-based reported previously (Xu et al, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Liu et al, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eIsotherms parameters for the adsorption of ions by the EDTA-CL at 30\u0026deg;C\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIons\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFreundlich\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLangmuir\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eD\u0026ndash;R\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eCd\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003cp\u003ePb\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003eF\u003c/sub\u003e = 59.7 L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e = 302.7 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13.1 mol kJ\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eb\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.037 L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003es\u003c/sub\u003e = 513.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9234\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9993\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9545\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003eF\u003c/sub\u003e = 75.2 L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e = 444.1 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003es\u003c/sub\u003e = 1117.2 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eb\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.153 L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;16.7 mol kJ\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9769\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9990\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9737\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.8 Kinetic\u003c/h2\u003e \u003cp\u003eThe kinetic data of adsorption of the metal ions are fitted using pseudo-first-order model (PFOM) (Lagergren, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1898\u003c/span\u003e), pseudo-second-order model (PSOM) (Ho \u0026amp; McKay, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1999\u003c/span\u003e) and Elovich model (EM) (Low, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e1960\u003c/span\u003e). The linear equations of these models are described in Supporting Information. In Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the PFOM and EM are not suitable for the description of the adsorption of the both ions by the EDTA-CL due to the low values of \u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e obtained from fitting curves of PFOM and EM. The values of \u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e derived from fitting curves of PSOM for the both ions are close to unity, whereas the calculated values and experimental values of the both ions by the EDTA-CL are very close to each other, illustrating that the PSOM can described well the adsorption of the EDTA-CL for the both ions.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eKinetic parameters for Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e at 30\u0026deg;C\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIons\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePFOM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePSOM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEM\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.070 min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.13\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e g mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eα\u003c/em\u003e\u0026thinsp;=\u0026thinsp;955.8 mg\u0026middot;g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u0026middot;min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCd\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e = 99.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e = 277.8 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eβ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.027\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9509\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9993\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9325\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.099 min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.91\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e g mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eα\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2748.7 mg\u0026middot;g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u0026middot;min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePb\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e = 146.7 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e = 434.8 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eβ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9990\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.8934\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.9 Thermodynamics\u003c/h2\u003e \u003cp\u003eThe calculated equations of Gibbs free energy change (Δ\u003cem\u003eG\u003c/em\u003e\u003csup\u003e0\u003c/sup\u003e), enthalpy change (Δ\u003cem\u003eH\u003c/em\u003e\u003csup\u003e0\u003c/sup\u003e) and entropy change (Δ\u003cem\u003eS\u003c/em\u003e\u003csup\u003e0\u003c/sup\u003e) are calculated as reported previously (Liu, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) and described in Supporting Information. In Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the values of ln\u003cem\u003eb\u003c/em\u003e from Langmuir constant increase as the temperature from 15 to 45\u0026deg;C, which leads to the increase of the Δ\u003cem\u003eG\u003c/em\u003e\u003csup\u003e0\u003c/sup\u003e values in the negative direction. These confirm that the adsorption of the EDTA-CL for the both ions is more spontaneous at higher temperature. The values of Δ\u003cem\u003eH\u003c/em\u003e\u003csup\u003e0\u003c/sup\u003e and Δ\u003cem\u003eS\u003c/em\u003e\u003csup\u003e0\u003c/sup\u003e for the both ions are positive, illustrating that the adsorption is endothermic and the randomness at the solid/solution interface is increased during the adsorption. These result in more adsorption at higher temperature.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThermodynamic parameters for adsorption of the Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e ions\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eConstants\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eCd\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003ePb\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u003csup\u003e\u0026deg;\u003c/sup\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003csup\u003e\u0026deg;\u003c/sup\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45\u003csup\u003e\u0026deg;\u003c/sup\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15\u003csup\u003e\u0026deg;\u003c/sup\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e30\u003csup\u003e\u0026deg;\u003c/sup\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e45\u003csup\u003e\u0026deg;\u003c/sup\u003eC\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eln\u003cem\u003eb\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e10.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eΔ\u003cem\u003eG\u003c/em\u003e\u003csup\u003eo a\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-23.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-26.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-28.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-19.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-21.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-22.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eΔ\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo b\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e26.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e17.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eΔ\u003cem\u003eS\u003c/em\u003e\u003csup\u003eo c\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e172.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e126.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u003csup\u003ea\u003c/sup\u003e Unit: kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003eb\u003c/sup\u003e Unit: kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003ec\u003c/sup\u003e Unit: J mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.10 Reusability\u003c/h2\u003e \u003cp\u003e0.2 mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl is used as the eluents to desorb the both ions from the loaded EDTA-CL with stirring for 1 h at room temperature and is shown 98.8% of Pb\u003csup\u003e2+\u003c/sup\u003e and 97.9% of Cd\u003csup\u003e2+\u003c/sup\u003e desorption. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e exhibits the adsorptive amounts of Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e ions by the regenerated EDTA-CL over five successive adsorption\u0026ndash;desorption cycles. The adsorptive amounts of the both ions drop per cycle of reuse. But even it remains 86.5% for Cd\u003csup\u003e2+\u003c/sup\u003e ions and 83.7% for Pb\u003csup\u003e2+\u003c/sup\u003e ions of the virgin at the end of 5th cycle. The EDS mapping of the N elements in the regenerated EDTA-CL is exhibited in Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, indicating that the N elements is uniformly dispersed on the surface of cellulose. The N contents of the regenerated EDTA-CL are found to be in the range of 7.1\u0026ndash;7.5 mmol g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e (Table S3). A decrease in the N contents of the regenerated EDTA-CL with the increase of the cycle numbers is observed. Compared with the N contents of the virgin (8.1mmol g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e), the loss of N elements is relatively low, which is consistent with the change in the values of RE%. These results illustrate that the EDTA-CL can be reused for several times without significant loss of the adsorptive amounts for the both ions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eEDTA-CL, an EDTA-like chelating material derived from cellulose, is obtained by the chemical grafting of amino acetic acid groups onto the cellulose through the Schiff base and substitution reaction. The EDTA-CL shows rapid chelation with Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e, high adsorptive amounts, and good regeneration. The EDTA-CL had a relatively large adsorptive amounts of 302.7 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Cd\u003csup\u003e2+\u003c/sup\u003e and 444.1 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb\u003csup\u003e2+\u003c/sup\u003e, as compared to many cellulose derivatives reported in the literatures. The EDTA-CL can offer chelating groups as effective binding sites and a homogenous surface for the adsorption of the both ions, leading to Langmuir model better fitting to the adsorptive behavior. The kinetic and thermodynamics fitting results means that an endothermic and spontaneous chemisorption between the N,O‑donor atoms on the surface of the EDTA-CL and the both ions is a rate-limiting step.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Supporting Information is available free of charge on the Springer Publications website at DOI:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work is supported by Scientific Foundation of Liaoning Education Department (LJKZZ20220053).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLu Yang: Investigation, Formal analysis, Data curation, Writing-Original draft preparation.\u003c/p\u003e\n\u003cp\u003eBaohong Ding: Methodology, Formal analysis, Writing-Original draft preparation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNan You: Conceptualization, Project administration Validation, Resources, Data curation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbu-Danso, E., Per\u0026auml;niemi, S., Leivisk\u0026auml;, T., Bhatnagar, A. 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(2014) Removal of Pb(II) and malachite green from aqueous solution by modified cellulose, Cellulose 21, 2797\u0026ndash;2809.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Scheme","content":"\u003cp\u003eScheme 1 is available in Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"EDTA-like, Chelation Cellulose, Heavy metals","lastPublishedDoi":"10.21203/rs.3.rs-3056356/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3056356/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCellulose is a renewable and promising material. However, native cellulose has to face the challenge of the removal of heavy metals with low efficiency which limits its application. In this work, a cellulose derivative with EDTA-like chelating groups is designed and prepared by the chemical grafting of cellulose. Cellulose is partially oxidized to dialdehyde cellulose which is treated with 20% excess of diethylenetriamine through a Schiff base reaction for the preparation of the aminated cellulose. The amine groups of the aminated cellulose are carboxymethylated by reacting with 20% excess of bromoacetic acid through a substitution reaction. A EDTA-like cellulose derivative functionalized with multidentate N,O‑donor atoms (EDTA-CL) is obtained for accessing the adsorptive property of Cd\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e. The high-efficient adsorption of the both ions by the EDTA-CL with high adsorptive amounts (Pb\u003csup\u003e2+\u003c/sup\u003e: 438.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and Cd\u003csup\u003e2+\u003c/sup\u003e: 287.2 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) can be accomplished by controlled parameters (pH in the range of 4\u0026ndash;6 with contact time 30 min) using the dosage of 1 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of the EDTA-CL in aqueous solution. The adsorptive processes of the both ions onto the EDTA-CL can be well fitted by pseudo-second-order and Langmuir equations. Thermodynamics data reveal that the adsorption of the both ions onto the EDTA-CL is a spontaneous and endothermic process. The loaded EDTA-CL by simple acid-base treatment can be regenerated 5 times with loss of adsorptive amounts (Cd\u003csup\u003e2+\u003c/sup\u003e: 14% and Pb\u003csup\u003e2+\u003c/sup\u003e: 17%).\u003c/p\u003e","manuscriptTitle":"Functionalized Cellulose with EDTA-like Chelating Groups for Removal of Heavy Metals","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-06-26 18:13:11","doi":"10.21203/rs.3.rs-3056356/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e22bc521-9e38-4222-9b70-61c1c0636b5e","owner":[],"postedDate":"June 26th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-10-02T14:29:23+00:00","versionOfRecord":[],"versionCreatedAt":"2023-06-26 18:13:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3056356","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3056356","identity":"rs-3056356","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}